CMOS fabrication of a light emitting diode based on silicon/porous silicon heterojunction

Abstract

The fabrication in a standard CMO line of a light emitting diode (LED) based on silicon/porous silicon heterojunction is discussed. To fabricate the LED in a CMOS line, the porous silicon formation must be performed either as the last or as an intermediate step. The former option requires a masking layer to protect the metallization level of the CMOS devices from the electrochemical solution for the porous silicon formation, whereas the latter forces an interruption in the process. Experimental test on several materials, routinely used in CMOS processes, show that no standard mask is suitable to fully protect the CMOS from the electrochemical etch. Hence porous silicon formation should be performed as an intermediate ste